Evidence Level
EAAs (Essential Amino Acids) are well-supported as a complete stimulus for muscle protein synthesis (MPS). Wolfe et al. (2017) demonstrated that all nine EAAs are necessary to maximize MPS, with the branched-chain amino acids (BCAAs) alone insufficient due to the rate-limiting role of the remaining six EAAs. Research by Borsheim et al. (2002) found that as little as 6 g of EAAs can effectively stimulate MPS, comparable to larger doses of whole protein, making them a calorie-efficient option. Furthermore, Paddon-Jones et al. (2004) showed that co-ingestion of protein and leucine with carbohydrates enhances muscle protein synthesis equally in both young and elderly individuals, highlighting their value for older adults. These findings underscore the importance of EAAs in supporting muscle recovery and growth, particularly in clinical populations and athletes training in a fasted state.